The invention relates to a method and arrangement for charging a telecommunication network subscriber by means of an intelligent network.
In telecommunication networks, intelligence relates to an ability to access stored data, process it and make decisions on the basis thereof. Current telecommunication networks, such as public switched telephone networks PSTN, are intelligent to some extent, since they are able to process stored data, for instance, in call routing. In the current telecommunication networks, a typical ‘intelligent’ facility is conditional call forwarding, which requires a call state analysis and call rerouting according to the stored service profile of the call forwarding. Intelligent facilities of this type have been an integral part of the basic network, so changing or adding facilities has required software updating in all switching centres of the network.
The intelligent network (IN) is a network architecture connected to the basic network (for instance, a fixed or a mobile network), enabling faster, easier and more flexible service implementation and service control. This is effected by transferring the service control from the switching centre to a separate functional IN unit. Thus the services become independent of the basic network operation, and the basic network structure and software need not be changed when services are altered or added.
IN standardization has progressed rapidly during the past few years. These standards define a certain functional and hierarchical model for the intelligent network. In said model, the service control is transferred from the switching centre of the basic network to a service control function (SCF) or a service control point (SCP) of the intelligent network. The service control function comprises all service logic and service-related control (for instance, the required database and service logic programs SLP, in other words, computer programs that implement the logic structure of a particular service, i.e. service logic). The service control logic can be a logic function alone which a service switching point (SSP) sees as an entity. The service switching point (SSP) is typically a switching centre, for instance a switching centre of the basic network, which implements a service switching function (SSF), i.e. IN service identification and initialization of interaction with the service control point (SCP). When a call involving an IN service is established, the service switching point SSP provides for connection arrangements. An IN service is produced such that in connection with encountering service-related detection points (DP) defined by the call state model (BCSM) which describes the call control operation, the IN service is started, whereby the SSP enquires instructions from the SCP. In other words, the SSP transfers control to the SCP and starts waiting for operations from the SCP. In connection with triggering the IN service, a service logic program SLP is started in the SCP, and the operation of the SLP defines the instructions that the SCP sends in each call phase to the SSP. The SSP interprets the instructions received and starts the required call control functions. To trigger an IN service refers to starting an IN service in response to an invocation generated when a particular identification condition is fulfilled.
The above describes the current structure of intelligent networks. In the present application, the intelligent network refers in general to a solution, in which a node conveying a call, session or packet data accesses a service control function that gives said node instructions to convey the call, session or packet data. Said node's access to the service control function is based on the service trigger data stored in the node. The intelligent network is characterized by triggers, state models and a controlling protocol or an API interface between the control function and the network switching node. The conveyance of the call, session or packet data can be described with a state model which is visible to the control function and which comprises phases and detection points related thereto, in which the processing can be stopped to wait for instructions from the control function. The controls and the operations can also be methods directed to call entities and event notifications related thereto.
The current IN solutions of various manufacturers are not necessarily compatible with each other and all manufacturers do not necessarily support the IN architecture of, for example, the GSM (Global System for Mobile Communications) network. Therefore, originating or transferred calls that employ IN services (for instance, the SCP-controlled chargeable announcements to subscriber) have to be routed to a centralized IN service switching point that is connected to the service control point of the same manufacturer.
A problem with the above-described arrangement is that the originating or transferred calls are generally charged in the originating switching centre or a transfer point. So when the intelligent network is used for charging, whereby the IN-assisted charging is effected in the centralized service switching point, the call tariff doubles since the originating switching centre or the transfer point also performs independent charging.